The long range goals of our research are to understand the regulation of individual genes in multigene families, and to understand evolutionary processes that give rise to families of genes in which different family members are differentially regulated. The studies in this proposal use the mouse urinary protein (MUP) gene family as a model system. MUP genes are present in 15-25 copies in the mouse genome and are expressed in the liver and in the submandibular glands. They are under the genetic control of a cis-acting regulatory locus. The major specific aim is to elucidate the organization of MUP genes and to identify possible regulatory sequences. The research will involve a combination of electron microscope techniques, restriction mapping, and DNA sequencing techniques, all applied to MUP genomic clones isolated from BALB/c and C57BL/10 recombinant DNA libraries in the Lambda phage vector Charon 4A. DNA sequences responsible for hormonal and strain-specific regulation of MUP genes will be identified through experiments involving introduction of MUP genes and chimeric plasmids containing portions of MUP genes into heterelogous cells by DNA mediated transformation. Given suitable progress in the aforementioned studies, questions concerning the influence of chromatin structure on gene expression will be studied. In particular, it will be determined whether DNAse-I hypersensitive sites appear in the liver prior to the time that MUP genes are transcribed in this tissue. We hope, also, that it will be possible to induce, in vitro, specific chromatin changes in the vicinity of MUP genes and thereby to search for soluble factors involved in regulation.